Was there life on Mars?

NASA Curiosity rover data just gave us one of the most tantalising hints yet that ancient Mars may have hosted microbial life.

NASA's Curiosity rover takes a cheeky selfie in 2018.

Cane you believe it?

Back in March 2025, scientists reported that Curiosity had sniffed out some seriously interesting substances in an ancient Martian mudstone in Gale Crater: molecules of decane, undecane, and dode cane.

These gorgeous long chains of carbon and hydrogen were the largest organic compounds ever found on Mars.

The word organic here is important. It means they were carbon-based, the fundamental building blocks that life as we know it depends on.

The researchers wondered if they might be fragments of fatty acids that had been sitting in that rock for billions of years.

Here on Earth, fatty acids are produced mostly by living things, though they can also be made through geologic processes.

This raises an obvious question. Were these molecules made by ancient Martian microbes, or just boring old geology? *

Finding these larger compounds provides the first evidence that organic chemistry advanced toward the kind of complexity required for an origin of life on Mars NASA, Curiosity mission page, 30 March 2025.

Curiosity’s data alone couldn’t answer that question. So scientists did some clever detective work.

Way back in the day.

In a new study just published in the journal Astrobiology, researchers combined lab radiation experiments, mathematical modelling, and Curiosity data to essentially “rewind the clock” about 80 million years.

That’s how long that particular rock has been sitting on the Martian surface, getting bombarded by cosmic radiation that slowly destroys organic molecules.

The team wanted to figure out: how much organic material would have been in that rock before all that radiation damage?

The answer: far more than typical non-biological processes could produce.

Super modelling.

After accounting for radiation degradation over those 80 million years, the researchers estimate the original concentrations would have been between 120 and 7,700 parts per million.

That’s higher than what the team could explain with known non‑biological sources like meteorites, interplanetary dust, atmospheric haze, and plausible geologic chemistry alone.

If known non-biological sources can’t fully explain the abundance, then it’s reasonable to hypothesise that living things could have formed them.

“The findings suggest a more speculative possibility: that some or all of the original organic material could have been produced by a hypothetical ancient Martian biosphere.” Jennifer L. Eigenbrode et al., Astrobiology 4 Feb 2026.

Hold your horses.

Before we start planning the Martian welcome party (I’d be plumping for “Insane in the Decane”), the researchers are quick to point out that more study is needed.

We still don’t fully understand how rapidly organic molecules break down in Mars-like rock under Mars-like conditions. And there might be other non-biological processes we haven’t thought of yet.

But here’s what we do know: this is some of the strongest evidence yet that the organic molecules Curiosity found are hard to explain without at least considering ancient Martian life as a possibility.

Not proof. Not even close.

But the most compelling hint we’ve ever had that Mars might have once been home to microbes billions of years ago.

And that’s pretty exciting.

* I know geology is not boring. But within the world of geology, this is way cool!

Hey I'm now also on substack.